1. Field of the Invention
The present invention relates to an apparatus for measuring the vibration characteristics, in particular operating resonant characteristics of a head gimbal assembly that is installed in a hard disk drive (HDD) incorporated in an information processing unit such as a computer.
2. Description of Related Art
The head gimbal assembly includes a head suspension and a slider to read and write a hard disk in a hard disk drive. The head gimbal assembly is oscillated at high frequencies with a voice coil motor (VCM), to move the slider from one track to another on the hard disk, or make the slider follow a track of the hard disk. To secure such operation of the head gimbal assembly, it is important to grasp the resonant characteristics of the head gimbal assembly.
There is a need of an apparatus capable of efficiently measuring head gimbal assemblies one after another for their resonant characteristics.
Recent HDDs read positioning signals at high sampling frequencies to improve positioning accuracy. Head gimbal assemblies employed for such HDDs must more accurately be measured for their resonant characteristics.
FIG. 20 shows an apparatus for measuring the resonant characteristics of a head gimbal assembly according to a related art. In FIG. 20, the apparatus has a shaker 101 to which a head gimbal assembly to be measured is attached. The shaker 101 has a shaker head 103 protruding outwardly. The shaker head 103 is a lightweight cylinder made of ceramics which is light. The shaker head 103 is provided with a threaded portion 105 for attaching the head gimbal assembly.
In order to measure the resonant characteristics, the head gimbal assembly is attached to the shaker head 103 by fastening a screw to the threaded portion 105. The shaker head 103 is light because it is made of ceramics, and therefore, is capable of measuring the head gimbal assembly at high frequencies.
According to the related art, a head gimbal assembly which is usually very small must individually be screwed to the shaker head 103. The fastening and unfastening of a head gimbal assembly to and from the shaker head 103 is laborious to limit the number of head gimbal assemblies to be measured. Accordingly, the related art is applicable only for a laboratory purpose and is hardly applicable for a manufacturing line.
Namely, the shaker head 103 made of ceramics is light and may be effective for measuring a head gimbal assembly at high frequencies. It, however, is inefficient to measure many head gimbal assemblies one after another.
The above-mentioned and other related arts are disclosed in Japanese Unexamined Patent Application Publication No. 2007-192735 and EMIC Corporation Catalogue No. 90201.